egg tart

n.

A tart is a pastry dish, usually sweet, similar to a pie, but different in that the top is open and not covered with pastry.

bad egg

Mainly American, informal.

Someone who behaves in a bad or dishonest way.

"Bad egg" is one of the few (possibly the only) English slang expressions that can be translated directly into Chinese, in which it is also slang and is understood to have exactly the same meaning.

eg.
He's a bad egg - don't believe anything he says.